Methods and apparatus for improved hydropower system

ABSTRACT

Methods and apparatus for improved power generation through movement of water retrofitting existing hydroelectric dams with draft tube inserts and tailrace walls to increase water velocity for production of power using hydrokinetic turbines installed in the tailrace. By initial design or by draft tube inserts and tailrace walls, increased and streamlined water flow leads to higher efficiencies of the hydrokinetic turbine, thus more efficiently converting available kinetic energy of the water into usable energy.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is based on provisional application Ser. No.60/859,789, filed on Nov. 17, 2006, which is incorporated as if fullyset forth herein.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable

DESCRIPTION OF ATTACHED APPENDIX

Not Applicable

BACKGROUND OF THE INVENTION

This invention relates generally to the field of energy and morespecifically to methods and apparatus for an improved hydropower system.

There are a variety of prior art systems for extracting power from waterbased systems such as dams, rivers and ocean flows. Several patentsdisclose a variety of after market retrofits for extracting hydropowerfrom river flow by inserting additional equipment at the base of the damto take advantage of the head potential present behind the dam. Forexample, U.S. Pat. Nos. 4,073,146, 4,078,388, 4,117,676, 4,159,188,4,165,467, 4,170,428, 4,261,171, 4,279,539, and 4,468,153 show aretrofit system for extracting energy out of the head potential of adam. None of these patents shows the innovative combination of thepresent invention and its use for increased extraction of kinetic flowenergy in a downstream system and innovative method of increasing flowvelocity for kinetic hydropower.

One of the current problems facing hydrokinetic power producers whenlocating hydrokinetic turbines downstream of existing dams is that thedesign of the draft tube at an existing dam (the draft tube conductswater from the outlet of the turbine to the body of water downstream ofthe existing dam) is specifically designed to dissipate kinetic energy.That is to say, the draft tube is a diffuser. The diffuser sometimestakes the shape of a conical fusta or an elliptically shaped conicalfusta due to underwater bathymetry. The end result of the draft tubediffuser is that the kinetic energy of the water is lowered, meaning thewater velocity is slowed. An additional problem that hydrokinetic powerproducers face at dams is that many tailrace designs dump water from theoutlet of the draft tube into an open body of water, such as a lake,reservoir, pool, or river to additionally dissipate the kinetic energyof the water in the tailrace exiting the draft tube.

BRIEF SUMMARY OF THE INVENTION

The primary advantage of the invention is to provide improvedhydrokinetic power system.

Another advantage of the invention is to provide a retrofit for existingdams to increase velocity of flow to a kinetic power system.

Another advantage of the invention is a method to retrofit existinghydropower dam system outflow draft tubes to lessen the loss of flowvelocity to improve efficiency and increase power in downstreamhydrokinetic turbines.

Another advantage of the invention is to provide wall system to channelflow to increase kinetic energy downstream of a dam for a hydrokineticpower system.

A further advantage of the invention is to provide a kinetic powersystem that utilizes increase flow dynamics in situ.

In accordance with a preferred embodiment of the invention, there isdisclosed a system for improved power generation having a dam storingwater as potential energy, one or more hydroelectric turbines positionedin the dam to receive the kinetic movement of water, one or more drafttubes to conduct water from the outlet of the hydroelectric turbines toa body of water downstream of the dam tailrace, one or more reciprocaldraft tube inserts placed in the draft tube to reduce the waterdiffusing characteristics of the draft tubes and increase water velocityat the draft tube outlets, and one or more hydrokinetic turbinesinstalled in the dam tailrace to produce energy from the water flowexiting the draft tube outlets.

In accordance with another preferred embodiment of the invention, thereis disclosed a system for improved power generation having a dam storingwater as potential energy, one or more hydroelectric turbines positionedin the dam to receive the kinetic movement of water, one or more drafttubes to conduct water from the outlet of the hydroelectric turbines toa body of water downstream of the dam tailrace, one or more wallsfixably attached to the dam tailrace bottom and draft tube outlet sideof the dam perpendicular to the dam to channel the dam outlet water, andone or more hydrokinetic turbines installed in the dam tailracereceiving the water flow channeled by the walls in the dam tailrace.

In accordance with a preferred embodiment of the invention, there isdisclosed a method for improved power generation having the steps ofstoring water as potential energy behind a dam, converting the potentialenergy to electricity by moving stored water through one or morehydroelectric turbines positioned in the dam to receive the water,conducting water through one or more draft tubes to from the outlet ofsaid hydroelectric turbines to the dam tailrace, reducing the waterdiffusing characteristics of the draft tubes and increasing watervelocity at the draft tube outlets through one or more draft tubeinserts, and positioning one or more hydrokinetic turbines in the damtailrace to produce energy from the water flow exiting the draft tubeoutlets.

Other objects and advantages of the present invention will becomeapparent from the following descriptions, taken in connection with theaccompanying drawings, wherein, by way of illustration and example, anembodiment of the present invention is disclosed.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings constitute a part of this specification and includeexemplary embodiments to the invention, which may be embodied in variousforms. It is to be understood that in some instances various aspects ofthe invention may be shown exaggerated or enlarged to facilitate anunderstanding of the invention.

FIG. 1 shows a schematic diagram of a power generating station on a damin a conventional configuration using head potential to generate powerthrough a turbine and outflow through a draft tube.

FIG. 2 shows a retrofit insert and draft tube exit wall in combinationwith a hydro kinetic turbine according to a preferred embodiment of thepresent invention.

FIG. 3 shows a plan view of a conventional draft tube and turbine powerassembly with attendant decrease in velocity of water exiting theturbine.

FIG. 4 shows a draft tube insert according to a preferred embodiment ofthe present invention and effective reduced diameter of draft tube forincreased velocity FIG. 5 shows a conventional power configurationwithout tailrace walls and attendant dissipated power potential tokinetic turbine downstream.

FIG. 6 shows tailrace walls for increased power potential to downstreamhydro kinetic power turbines in multiple wall configurations and shapes.

FIG. 7 shows a cross sectional view of a representative tailracevertical wall and tailrace box wall.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Detailed descriptions of the preferred embodiment are provided herein.It is to be understood, however, that the present invention may beembodied in various forms. Therefore, specific details disclosed hereinare not to be interpreted as limiting, but rather as a basis for theclaims and as a representative basis for teaching one skilled in the artto employ the present invention in virtually any appropriately detailedsystem, structure or manner.

A system to retrofit existing hydropower dams so that the kinetic energyin the tailrace (the tailrace is the body of water directly at theoutlet of the draft tube) can be increased for higher hydrokineticenergy production at a downstream hydrokinetic energy generating powerstation. FIG. 1 shows a conventional power system 10 where head powerfrom the upstream water blocked by a dam 12 is used to drive turbine 14to generate power. Outflow of turbine 14 is through draft tube 16 whichdissipates the flow of water from the turbine to reduce turbulence andother negative effects.

As previously mentioned, one of the current problems facing hydrokineticpower producers when locating hydrokinetic turbines downstream ofexisting dams is that the design of the draft tube at an existing dam(the draft tube conducts water from the outlet of the turbine to thebody of water downstream of the existing dam) is specifically designedto dissipate kinetic energy. The end result of is that the kineticenergy of the water is lowered, meaning the water velocity is slowed,thus reducing potential capture of energy.

A hydrokinetic turbine, one which operates solely on the water velocity,and not the pressure head of impounded water, from a theoreticalstandpoint, require the highest possible water velocity and the largestpossible turbine diameter in order to generate the greatest amount ofpower possible.

By installing a retrofit to the draft tube of the existing dam ordesigning the draft tube for optimal flow can result in a significantincrease in the streamlined or turbulent flow velocity at the outlet ofthe draft tube, resulting in a much higher velocity at the downstreamhydrokinetic turbine thereby increasing the power output. This can beaccomplished in a number of ways by adding a retrofit draft tube insertor initially designing a draft tube for a new dam such that thediffusing rate that is lower but still of a diffusing design (the ratioof area's is still positive) or have a constant diameter draft tube orslightly decrease the draft tube diameter to compensate for minorfrictional losses in the draft tube due to the materials of constructionof the draft tube.

In a preferred embodiment, the flow may be streamlined as it lendsitself to higher efficiencies of the hydrokinetic turbine, thus moreefficiently converting available kinetic energy of the water into usableenergy (shaft work).

FIG. 2 shows a combination of an insert to the draft tube and exit wallaccording to a preferred embodiment of the invention. Power system 20has one or more conventional turbines 24 placed in dam 22 for generationof power from the head potential of the dam. A draft tube 26 is fittedwith a reciprocal tube insert 28 for changing the flow characteristicsof the tube. Preferably, but not required in all situations, is drafttube exit wall 30 placed in line with the inserted tube 28 to furtherchannel the flow of water to the hydrokinetic turbine 32.

Reciprocal tube insert 28 can be designed in several ways including as apermanent retrofit or a temporary retrofit that could be removed orreplaced. Further, the draft tube insert may be made from many materialsof construction including, but not limited to, reinforced concrete;metals of various types; wood; and reinforced or non-reinforcedsynthetic material (for example, plastics), to name a few.

FIG. 3 shows the flow characteristics of a convention draft tube system.Turbine 34 generates power from water flow that exits through the drafttube 39. The flow rate remains constant where A_(i) 36 is the draft tubecross sectional area closest to the turbine, and A_(o) 37 is the crosssectional area farthest from the turbine. Notably, velocity v_(i) 35 issubstantially higher than v_(o) 38 demonstrating that the draft tubedecreases velocity of water exiting turbine 34.

FIG. 4 shows a power system 40 having conventional turbines with drafttube 44 retrofitted with tube insert 42 reducing the old diameter 46 ofthe draft tube to new diameter 48 which increases the velocity of theexiting water.

FIG. 5 shows a power system 50 for converting river flow throughturbines to electrical energy. Turbines 52 are placed in a conventionalmanner whereby flow velocity v₁ 54 is higher than flow velocity v₀ 56.Without the additional of tailrace walls, the kinetic energy at thedraft tube dissipates radially outward proportional to the followingequation: KE=½ mv².

Since velocity is directly proportional to the inverse of the square ofthe distance from the draft tube, flow velocity v₁ 54 is significantlyhigher than flow velocity v₀ 56. Therefore, power potential forhydrokinetic turbine 58 is reduced and inefficiently low. To increasethe flow characteristics for the hydrokinetic turbine, tailrace wallsmay be preferably placed at the output of the draft tubes.

By inserting a wall in between each draft tube outlet, the kineticenergy of the water is forced into a more constant cross sectionalchannel which also has the effect of preventing or reducing the rate ofthe dissipation of kinetic energy from the water resulting in higherwater velocities (higher kinetic energy) further downstream. Anotherenhancement to the insertion of walls in between the draft tube outletsis to install a floor below the draft tube outlets that extendsdownstream with the walls that have been installed creating a channel.By keeping the cross sectional area of the channel for the flowing waterrelatively constant, additional increases in the kinetic energy of thewater can be obtained which increases the quantity of power generated bythe hydrokinetic system.

FIG. 6 shows a power system 60 with conventional turbine room 64 forgenerating hydroelectric power from a river. As water flows through theturbines out the draft tube outlets, it is channeled by tailrace walls66 that direct the water and increase velocity of flow to high powerpotential hydrokinetic turbines 68. By doing so, the tailrace wallsgreatly increase the velocity of downstream flow to the hydrokineticturbines thereby generating significantly higher amounts of power.

FIG. 7 shows an embodiment of the tailrace and channel walls and orfloors such as vertical wall 70 and box wall 72. The combination ofwalls and floors of the channel can be in many shapes including, but notlimited to, vertical parallel walls only; walls and floor that create a“U” shape; walls and floor that create a “U” shape, but converge thefurther downstream from the draft tube to keep the kinetic energy high;walls that form a “V”; walls that are fully submerged; and walls thatare partially submerged.

The optimal system for the highest possible hydrokinetic powergeneration system downstream of a dam for a given dam design may be acombination of both a modified draft tube as shown in FIG. 2 andtailrace and channel walls and or floors as shown in FIGS. 6 and 7.

While the invention has been described in connection with severalpreferred embodiments, it is not intended to limit the scope of theinvention to the particular form set forth, but on the contrary, it isintended to cover such alternatives, modifications, and equivalents asmay be included within the spirit and scope of the invention as definedby the issued claims.

1. A system for improved power generation through movement of watercomprising: a dam storing water as potential energy; one or morehydroelectric turbines positioned in said dam to receive the kineticmovement of water; one or more draft tubes to conduct water from theoutlet of said hydroelectric turbines to a body of water downstream ofthe dam tailrace; one or more reciprocal draft tube inserts placed ineach of said draft tubes to reduce the water diffusing characteristicsof said draft tubes and increase water velocity at said draft tubeoutlets; and one or more hydrokinetic turbines installed in said damtailrace to produce energy from the water flow exiting said draft tubeoutlets.
 2. A system for improved power generation through movement ofwater as claimed in claim 1 wherein said draft tube insert ispermanently and fixably attached to and mounted inside said draft tube.3. A system for improved power generation through movement of water asclaimed in claim 1 wherein said draft tube insert is removably attachedto said draft tube.
 4. A system for improved power generation throughmovement of water as claimed in claim 1 wherein said draft tube insertis manufactured from reinforced concrete.
 5. A system for improved powergeneration through movement of water as claimed in claim 1 wherein saiddraft tube insert is manufactured from synthetic material.
 6. A systemfor improved power generation through movement of water as claimed inclaim 1 wherein said draft tube insert is manufactured from metal.
 7. Asystem for improved power generation through movement of watercomprising: A dam storing water as potential energy; One or morehydroelectric turbines positioned in said dam to receive the kineticmovement of water; One or more draft tubes to conduct water from theoutlet of said hydroelectric turbines to a body of water downstream ofthe dam tailrace; One or more walls fixably attached to the dam tailracebottom and draft tube outlet side of said dam perpendicular to said damto channel said dam outlet water; and One or more hydrokinetic turbinesinstalled in said dam tailrace receiving said water flow channeled bysaid walls in the dam tailrace.
 8. A system for improved powergeneration through movement of water as claimed in claim 7 furthercomprising one or more floors fixably attached to the dam tailracebottom and draft tube outlet side of said dam perpendicular to said damto channel said dam outlet water.
 9. A system for improved powergeneration through movement of water as claimed in claim 7 wherein saidwalls form a “U” shape.
 10. A system for improved power generationthrough movement of water as claimed in claim 7 wherein said walls forma “U” shape close to the draft tube outlet and converge downstream toincrease kinetic energy prior to said water flow entering saidhydrokinetic turbine.
 11. A system for improved power generation throughmovement of water as claimed in claim 7 wherein said walls form a “V”shape.
 12. A system for improved power generation through movement ofwater as claimed in claim 7 wherein said walls are fully submerged inthe dam tailrace.
 13. A system for improved power generation throughmovement of water as claimed in claim 7 wherein said walls are partiallysubmerged in the dam tailrace.
 14. A system for improved powergeneration through movement of water as claimed in claim 7 furthercomprising one or more reciprocal draft tube inserts placed in saiddraft tube to reduce the water diffusing characteristics of said drafttubes and increase water velocity at said draft tube outlets.
 15. Amethod for improved power generation through movement of watercomprising the steps of: storing water as potential energy behind a dam;converting said potential energy to electricity by moving stored waterthrough one or more hydroelectric turbines positioned in said dam toreceive said water; conducting water through one or more draft tubesfrom the outlet of said hydroelectric turbines to the dam tailrace;reducing the water diffusing characteristics of said draft tubes andincreasing water velocity at said draft tube outlets through one or moredraft tube inserts; and positioning one or more hydrokinetic turbines insaid dam tailrace to produce energy from the water flow exiting saiddraft tube outlets.
 16. A method for improved power generation throughmovement of water as claimed in claim 15 further comprising the steps ofchanneling water to said hydrokinetic turbines by means of one or morewalls fixably attached to the dam tailrace bottom and draft tube outletside of said dam perpendicular to said dam.
 17. A method for improvedpower generation through movement of water as claimed in claim 15further comprising the steps of channeling water to said hydrokineticturbines by means of one or more walls fixably attached to the damtailrace bottom and draft tube outlet side of said dam perpendicular tosaid dam.
 18. A method for improved power generation through movement ofwater as claimed in claim 15 further comprising the steps of increasingwater velocity in the dam tailrace by means of shaped walls convergingdownstream to increase kinetic energy prior to said water flow enteringsaid hydrokinetic turbine.